Counterbalancing means for expansion roofs



Oct. 17, 1944i 7 T. b. LARSEN 2,360,692

COUNTERBALANCING MEANS FOR EXPANSION ROOFS Filed Aug. 14, 1941 2Sheets-Sheet 1 INVENTOR. Q Q BY 0 Aarzserz Q Oct. 17, 1944. T, o. LARSEN2,360,692

COUNTERBALANCING MEANS FOR EXPANSION 'ROOFS Filed Aug. 14, 1941 2Sheets-Sheet 2 INVENTOR.

J "6 0; lar'aen/ BY @r/ Patented Oct. 17, 1944 UNITED STATES PATENTOFFICE COUNTERBALANCIN G MEANS FOR EXPANSION ROOFS Thyge O. Larsen,Hammond, Ind., assignor to Graver Tank & Mfg. 00., Inc., Catasauqua,Pa... a corporation of Delaware Application August 14, 1941, Serial No.406,837

8 Claims. (01. 48176) The invention relates to storage tanks for'storing either gases or vapors or volatile liquids and the vaporsarising therefrom and has reference more particularly to improvedcounterbalancing means for the expansion type of roof as shown in thepatent to Phillip S. Graver No. 2,277,398, granted March 24, 1942, andentitled Expansion roof for oil storage tanks.

In the type of tank above referred to, the roof in moving verticallyupward provides increased vapor space for the expanding gases andvapors. Said gases and vapors expand during the heat of the day andunless they are Withdrawn from the tank or additional space within thetank is provided they produce a serious increase in pressure on the roofof the tank. When the tank is storing volatile liquids additional vaporsare produced during the day as a result of evaporation. However, ifthese vapors are conserved they can be reclaimed during the night owingto the cooler night temperature which condenses the vapors. Theproduction of vapors during the day followed by subsequent cooling andcon- (lensing of the vaporsduring the night is known as .breathing andinlarge tanks, particularly if only partly filled, such breathing willbe substantial. I

It is well known that severe evaporation losses will result during thestoring of volatile liquids such as gasoline or the like if the vaporsare expelled to the atmosphere in order to relieve the pressure withinthe tank. Therefore, as a matter of economy it is necessary to conservethe vapors so that they can be eventually condensed without any loss ofthe valuable fractions. For these and other reasons it is desirable toequip oil storage tanks with an expansion roof capable of considerablemovement in a vertical direction to vary the vapor space within thetank. Thus in expansion roof tanks it is not necessary .to discharge anyvapors to the atmosphere even under the most severe breathingconditions.

Greater possibilities are offered when an expansion roof tank isconnected to a number of existing old tanks providing breathing spacetherefor. Since it is not practicable to reinforce the roofs of the oldtanks the invention provides counterbalancing means for expansion rooftanks whereby the effective pressure for operating the same can be madeto conformto a safe pressure for the old tanks.

Therefore an object of the invention is to provide novelcounter-balancing means forexpansion roof tanks whereby the rool can beoperated at any desired pressure below that caused by the actual weightof the roof. 7

Another object of the invention is to provide improved counter-balancingmeans for expansion roof tanks wherein the effective weight of thecounter-balancewill not vary even though the tank may be partly full ofliquid or, substantially empty.

A further object of the invention is to provide counterbalancing meansfor a movable roof which in additionto its counter-balancing functionwill have operation to maintain the roof substantially horizontal duringvertical movement thereof.

With these .and various other objects in view,

the invention .may consist of certain novel features of construction andoperation as will be more fully described and particularly pointed outin the specification, drawings and claims appended hereto.

.In the drawings which illustrate an embodivment of the invention andwherein like reference characters are used to designate like parts-Figure 1 isa view illustrating one embodiment of the invention with thetank beingshown in section and with the roof in deflated position,

which locates the counter-balance in its upperthe center column of thetank and positioned concentrically within a retaining well therefor.

Referring more in detail to the drawings, particularly Figure l, theexpansion roof tank selected for illustrating the invention includesside walls 10, a bottom wall H adapted to rest on the earth or othersuitable support and a supporting structure including a center post [2hav- I! is provided so that the weight on the center post will be moreevenly distributed to the ground. The cylindrical walls Ill of the tankare suitably reinforced at their upper end by means of inwardly directedshell girders, to be more particularly described, which provide guidingmeans for posts depending from the expansion roof and supporting meansfor the sheaves having contact with flexible cables. I

The present tank is provided with an outside launder l8, which is bestshown in Figure 2. The base of the launder is formed by the angle piece20 extending around the circumference of the tank, the same having areinforcing part 2| associated therewith and which forms the base properof the launder. Upstanding plate members 22 and 23 have securement toeach other and to the angle 20 so as to form the launder with thecylindrical wall of the tank and which in effect provides a trough forcontaining a liquid such as gasoline or oil to form a seal with respectto the bell holder type of roof. Members 22 and 23 are reinforced attheir upper end by outwardly directed angle pieces 24 and 25.

The open top tank so far described is closed by means of a movable roofin the form of a holder bell so as to provide for the necessaryexpansion in the event of increased pressure on the part of the gases orvapors housed within the tank. The movable roof in the form of a holderbell is indicated in its entirety by numeral 26, the same havingtelescoping relation with respect to the upper portion of thecylindrical wall III.

The bell includes a cambered roof 2'! having,

a depending skirt 28 for location within the launder and also having adepending rain shed skirt 30 which forms a cover for the launder,protecting the same from the weather. The rain shed skirt is concentricwith skirt 28 and the same is suitably secured to the outer periphery ofthe roof by the angle 3|, Figure 2, which in turn is secured to ahorizontally disposed outer extending rafters 36, Figure 1, which uniteat the apex of the roof, being securely joined to the center piece 31which rests on the cap l3 when the movable roof is in deflated position.

Depending post 38 are provided for guiding and controlling the verticalmovements of the.

holder bell including the cambered roof 2'! and the depending skirt 28.The posts are suitably fastened to the roof by means of the plates 35 towhich the upper end of each post is respectively welded as at 39. Theposts depend vertically downward, passing through openings pro.

vided therefor in the inwardly extending shell and down movement andparticularly to guide .75

the post and partly anchor the lower end thereof when the roof is fullyinflated. The bracket 43, located below the rollers, provides a supportfor journalling at its outer end the sheave 44 which has contact wtih aflexible cable or chain 45 extending around said sheave and travellingdownward in parallel relation with the post, being fixed to the lowerend thereof by means of connection 46. Two brackets 43 are provided foreach sheave and which are located on the respective sides of the post,being welded at their inner ends to the cylindrical wall Id of the tankand at their outer end to the uprights 4'5. Uprights 41 are in turnsupported by the shell girder 48 having an opening 49 therethrough topermit passage of the post and its chain connection 46. A similar shellgirder 56 is located immediately below 48, the same likewise having anopening 5| for accommodating said post. The last shell girder 52 issuitably secured to the inner walls of the tank in substantialhorizontal alignment with the base of the launder. The shell girder atthis point help to reinforce the tank and the same also providessupporting means for the depending collar 53 which provides an openingof suflicient size to accommodate the post and chain connection 46. Theposts are spaced circumferentially around the inside of the tank and thevarious girders above defined have openings as described foraccommodating a post. As shown in Figure 2 the roof is in deflatedposition and accordingly the depending skirt 28 extends substantially tothe bottom of the launder and each depending post 38 extends through thelowermost sheave 52 through collar 53 thereof for a short distance belowsaid collar, all as shown in said figure.

During vertical movement of the expansion roof herein disclosed it Willbe seen that the depending posts 38 are guided by the rollers 4| whichfacilitate movement and thereby maintain the roof horizontally disposed.In addition to being guided by the rollers certain depending posts haveconnection with cable means such as 45 in the form of a flexible cableor chain. As previously explained, the chain connects with the extremelower end of its respective depending post as at 46, the post having aplate 54 welded thereto for the purpose. The chain extends substantiallyparallel with its post and passes over the sheave 4-4 suitablyjournalled adjacent the post by the sheave bracket 43. In accordancewith the invention the several chains 45 from the circumferentiallypositioned posts 38 have connection with counterbalancing means whichact in a direction to facilitate upward movement of the expansion roof.Thus by counter-balancing the weight of the roof the same will operateat a pressure considerably below the pressure which would otherwise berequire-d.

Each flexible chain 45 extends radially inward toward the center post[2, having a turnbuckle 55 interposed in its length for purposes ofadjustmenuand passes over a sheave 56 which directs the flexible chaindownwardly in parallel relation with the center post 12. Each of thesheaves 56 is suitably journalled by brackets 51 secured to the centerpost. The flexible chains 45 extend from the sheaves 56 almost to thebase of the center post where said chains connect with a. substantiallycircular counter-weight 58. Connection between the chains and thecounterweight may be effected by the eyelets 59 embedded in thecounter-weight and to which the chains are secured. Since the dependingposts 38; are circumierentially' disposed around the interior of thetank itwill be understood that the brackets 51 and sheave 56 will extendradially from the center post l2,'ha.Vlng substantial alignment withtheir respective depending post. The counterweight 58' will also haveconnection at circumferentially spaced points with the flexible chains.Said counter-weight has a substantiallysquare center opening 60 forreceiving the center post and for purposes to be presently described thecounter-weight is positioned within a cylindrical wellformed by thecircular member 6|; Said member extends vertically upward from thebottom wall H, being welded thereto so that the well will contain aquantity of liquid such as gasoline or oil. -When the expansion roof isin deflated position, such as shown in Figure 1, in which position theroof is supported by the center postl2 and by the cylindrical walls IDof the tank, it will be understood that the counterweight is located'inits uppermost position. The action of the counter-weight is impartedthrough the flexible chainsto the depending posts and which is in adirection to urge said posts and thus the roof to move verticallyupward. By selecting a counter-Weight of proper weight for theparticular roof associated therewith the roof can be made to operate atvery low vapor pressures.

It is of course necessary that the effective action of thecounter-weight 58 remain constant, irrespective of whether the tank isfull of liquid or empty. When the counter-weight is immersed in a liquidits action is reduced to a certain extent due to' the'buoyant effect ofthe liquid thereon. Were it not for the well 6|, which retains aquantity of liquid for the counter-weight its effective action would beentirely different for an empty tank in comparison to a tank containingsome liquid. Therefore the action of the well is to' maintain thecounter-weight submerged at all times and'its action is thereforeindependent of the existing oil storage capacity of the tank.

During operation of the expansion roof it will' be understood that thelaunder l8 will contain oil or water as a sealing mediumfor thedepending skirt 28. The tankmay also contain oil, in which case themovable roofwill be subjected to varying vapor pressures. The action ofthe counter-weight 58 is to materially lessen the weight of the holderbell 26 including that of the posts 38 depending therefrom. Thus at apredetermined vapor pressure the roof willrise to increase the spacewithin the tank. When the present tank is connected to oil storage tanksso as to relieve the pressures on the roofs thereof the vapors and gasesare conducted to and from the conduit 62. As a result of thecounterweight for the expansion tank the movable roof can be adjusted torise at vapor pressures which are safe pressures for the oil storagetanks.

The invention is not to be limited to or by details of construction ofthe particular embodiment thereof illustrated by the drawings, asvarious other forms of the device will of course be apparent to thoseskilled in the art without de' parting from the spirit of the inventionor the scope of the claims.

What is claimed is:

1. A storage tank comprising a substantially cylindrical shell, avertically movable roof, sealing means between the shell and the roofwhereby the roof may move vertically with respect thereto to vary thevapor space within'the tank, guiding means for guiding the roof in itsvertical movements including posts depending from thereof and havinglocation within the tank, counterbalancing meansfor said roof includinga movable counter-weight, and flexible means connecting thecounter-weight with eachdepending post respectively at the lower endthereof and in a. manner to exert an upwardforce on each depending post,the weightof the counter-weight being such that the sumof'the upwardforces exerted on the depending posts is equal to 'or less than theweight of the roof, whereby relatively low pressures within the vaporspace will cause vertical movement of the roof.

2. A storage tank comprising a substantially cylindrical shell, avertically movable roof, sealing means between the shell and the roofwhereby the roof may move vertically with respect thereto to vary thevapor space within the tank, guiding means for guiding the roof in itsvertical movements includin posts depending fromthe roof and havinglocation within the tank, rollers supported from said cylindrical shelland having contact with the depending posts respectively for guiding thesame during said vertical movement, counter-balancing means for saidroof including a movable counter-weight having flexible means connectingthe counter-weight with each 'depending post at the lower end thereofand in a manner to exert an upward force on each depending post, theweight of the counter-weight being such' that the sum of the upwardforces exerted on the depending posts is equal to or less than theweight of the roof, whereby relatively low pressures within the vaporspace will cause vertical movement of the roof, and sheaves havingcontact with each said flexible. means intermediate the ends thereof.

3. A storage tank comprising a substantially cylindrical shell, avertically movable roof, sealing means between the shell and the roofwhereby movements including posts depending from the a roof and havinglocation within the tank, rollers supported from saidrcylindrical shelland having contact with the depending posts respectively for guiding thesame during said vertical movement, counter-balancing means for saidroof in.- cluding a movable counter-weight having flexible meansconnecting the counter-weight with each depending post at the lower endthereof and in a manner to exert an upward force on each depending post,the weight of the counter-weight being such that the sum of the upwardforces exerted on the depending posts is equal to or less than theweight of the roof, whereby relatively low pressures within the vaporspace will cause vertical movement of the roof, and sheaves havingcontact with each said flexible means intermediate the ends thereof,certain of said sheaves being supported from the cylindrical shell ofthe tank.

4. In a storage container for gas or liquid, in combination, an open toptank, an expansion roof for said tank movable with respect thereto tovary the vapor space within the tank, means providing a seal between thetank and roof so as to confine vapors within the tank, a plurality ofposts fixed to the roof at circumferentially spaced points and dependingwithin the tank, a center supporting column within the tank forcentrally sup orting the roof in deflated position, a counter-balancingweight for said roof having encircling relation with saidcentersupporting column, and flexible meansconnecting the counterbalancingweight with certain of said depending posts respectively at the lowerend thereof and in a manner to exert an upward force on each dependingpost, the weight of the counter-weight being such that the sum of theupward forces exerted on the depending posts is equal to or less thanthe weight of the roof, whereby relatively low pressures within thevapor space will cause vertical movement of the roof.

5. In a storage container for gas or liquid, in combination, an open toptank, an expansion roof for said tank movable with respect thereto tovary the vapor space within the tank, means providing a seal between thetank and roof so as to confine vapors within the tank, a plurality ofposts fixed to the roof at circumferent'ially spaced points anddepending within the tank, a center supporting column within the tankfor centrally supporting the roof in deflated position, means forcounter-balancing the weight of said movable roof to facilitate upwardmovement thereof including a counter-weight having encircling relationwith the center supporting column, flexible means connecting thecounter-weight with each depending post respectively at the lower endthereof, and sheaves having contact with each said flexible means, theweight of the counterweight being such that the sum of the upward forcesexerted on the depending posts is equal to or less than the weight ofthe roof.

6. In a storage container for gas or liquid, in combination, an open toptank, an expansion roof for said tank movable with respect thereto tovary the vapor space within the tank, means providing a seal between thetank and roof so as to confine vapors within the tank, a plurality ofposts fixed to the roof at circumferentiallyspaced points and dependingwithin the tank, a, center supporting column within the tank forcentrally supporting the roof in deflated position, means forcounter-balancing the weight of said movable roof to'facilltate upwardmovement thereof including a counterweight having encircling relationwith the center supporting column, flexible means connecting thecounter-Weight with each depending post respectively at the lower endthereof, and sheaves having contact with each said flexible means,certain of said sheaves being supported from the cylindrical shell ofthe tank, and other sheaves being supported from the center supportingcolumn, the weight of said counterweight being such that the sum of theupward forces exerted on the depending posts is equal to I or less thanthe weight of the roof.

V 7. In a storage container for gas or liquid, in combination, an opentop tank, an expansion roof for said tank movable with respect theretoto vary the vapor space within the tank, means providing a seal betweenthe tank and roof so as to confine vapors within the tank, a pluralityof posts fixed to the roof at circumferentially spaced points anddepending within the tank, means having rolling contact with each postfor guiding the posts in their vertical movements, a sheave positionedadjacent each'post and located near the upper end of the open top tank,a center supporting column located within the tank for centrallysupporting the roof in deflated position, a plurality of sheavessupported by said center column, counter-balancing means for the roofincluding a counter-weight having encircling relation with said centercolumn, and flexible means connecting the counter-weight with eachdepending post respectively at the lower end thereof, each said flexiblemeans passing over one of the sheaves supported by the column and havingcontact with the sheave adjacent its particular depending post, theweight of said counter-weight being such that the sum of the upwardforces exerted on the depending posts is equal to or less than theweight of the roof.

8. In a storage container for gas or liquid, in combination with an opentop tank, an expansion roof for said tank movable with respect theretoto vary the vapor space within the tank, means providing a seal betweenthe tank and roof so as to confine vapors within the tank, a pluralityof posts fixed to the roof at circumferentially spaced points anddepending within the tank, a center supporting column within the tankfor centrally supporting the roof in deflated position, acounter-balancing weight for said roof having encircling relation withsaid center supporting column, flexible means connecting thecounter-balancing weight with certain of said depending postsrespectively at the lower end thereof and in a manner to exert an upwardforce on each depending post, the weight of the counter-weight beingsuch that the sum of the upward forces exerted on the depending posts isequal to or less than the weight of the roof, whereby relatively lowpressures within the vapor space will cause vertical movement of theroof, a well provided at the base of the center supporting column insurrounding relation therewith, and a liquid in said well for immersingthe counter-weight whereby its effective counter-balancing action issubstantially uniform irrespective of the quantity of liquid storedwithin the tank.

THYGE o. LARSEN

